In the manufacture of construction of reactors, pipes, valves, and other enclosed fluid-handling process equipment it is often necessary to employ welding operations to join component parts together. Where such equipment is designed to handle corrosive fluids, precautions must be taken to keep the fluids from contacting the equipment. As a result, individual components such as pipes may be coated on their interior surfaces to protect the surfaces from the action of the corrosive materials. However, when the inner surface of the finished article is subjected to a welding procedure, the now inaccessible inner surface coating is generally damaged, either by the welding operation itself, or by removal prior to welding to prevent contamination of the weld area, leaving an exposed area subject to corrosion. It is therefore highly desirable to find a means of protecting such an exposed area and further to find a means which may be inserted into the pipe section while it is accessible. To this end, an internal pipe protection device has been developed and is the subject of co-pending and co-assigned U.S. patent application Ser. No. 174,304, filed July 31, 1980. The aforementioned device may be inserted into a pipe section before the welding of said section to an adjoining section. Subsequent to the welding procedure, and after the weld area has cooled, the pipe protection device may be positioned directly under the weld area and remotely activated to provide a protective lining for said exposed section. The problem of moving such a pipe protection device or other similar device (hereafter referred to generally as a "payload") is solved by the instant invention, which is a remotely thermally activatable device for accurately delivering a payload to a pre-determined location within a pipe.
The problem of the placement of devices within a pipe has been addressed previously. For example, U.S. Pat. No. 3,135,047 to A. R. Houser discloses the use of propping supports to position a backing member within a pipe during a welding operation. Houser specifically teaches that such a propping support should be removable and to that end may be made of a substance which may be dissolved or broken up and flushed from the relatively inaccesible chamber. In the instant invention, the payload requires more than just radial and axial support within the pipe since it must be sufficiently remote from, for example, a welding area in order to prevent its damage or premature activation. The instant invention provides a solution to that problem by providing a unique device which will support and shield a payload until such time as the device is thermally activated by the heating of the pipe in its vicinity, causing it to move the payload to the desired position, and align the payload for operation. Therefore, the instant invention provides a dynamic apparatus for solving a problem previously considered capable of only a static solution.